Titanium oxide has been used as a photocatalyst for many different applications. One of the most studied applications is for solar cell applications. There are many other applications that are already used in products. Titanium dioxide (TiO2) is used to absorb ultraviolet (UV) rays in sun screen lotions. TiO2 is also used to clean water and air in purification systems. The TiO2 works by creating free radicals and charged particles that will react with bio and viral contaminants and noxious chemicals near the activated TiO2, thus decomposing these contaminants into harmless compounds.
In these purification systems, a UV light source is required to activate the TiO2 material. The photocatalytic behavior is best if the wavelength of the UV light used is shorter than 380 nm. Typically, a fluorescent lamp (sometimes called an inverter lamp) is used as the UV light source. There are several problems with these UV light sources. They often contain mercury and are thus toxic to the environment and to humans since they are often disposed in a landfill. Mercury lamps also take some time to switch ON to full power, i.e., they have a warm-up period. If the lamps break in the home air system or water supply, they will contaminate these systems with toxic mercury. Further, the life of these systems is limited and the intensity of the UV light is weak, thus limiting the usefulness of the decontamination or cleaning system using the TiO2 photocatalyst.
Another source of UV light is using wide bandgap LEDs (light emitting diodes). Although LEDs have longer lifetimes and are instant ON, they are not efficient and do not illuminate uniformly.
What is needed is a large area UV light source that is instant ON, does not contain mercury, has high brightness, is highly efficient and has long lifetimes.
Furthermore, the TiO2 is currently deposited on the UV lamp surface or on a fiberglass cloth. The fiberglass cloth is needed because the TiO2 deposition requires high temperatures to achieve the best photocatylitic properties of the TiO2. This material is not conductive and may not be robust. What is needed is a cloth or fiber material on which to deposit the TiO2, which is conductive and able to withstand high temperatures.